U.S. Pat. No. 3,113,052 in the name of Kenneth H. Schneck discloses a method for producing extrusions of aluminum-magnesium silicide alloy. An unrecrystallized, precipitation hardened product is obtained, having uniform strength and elongation properties.
It is also known to produce precipitation hardened aluminum alloy 6061 cylinders of high strength and good bendability by cold drawing subsequent to extrusion. The strain introduced into the metal by the cold working nucleates more grains and hence gives a finer overall grain size when recrystallization occurs during the solution heat treat.
U.S. Pat. No. 3,847,681 refers to a coarse precipitate structure, followed by deformation to introduce strain energy, followed by heating to effect fine-grained recrystallization.